Rotary machines typically utilize motors that are powered pneumatically or electrically so as to cause rotation of the output shaft which is utilized for a given purpose, such as powering a drill, saw and the like. As is well known surgical drills are typically hand-held and for its effective use, the surgical drill should be as quiet as possible, free of vibrations and have a good feel to afford the surgeon the efficacy of the motor when used in surgical procedures.
We have found that by utilizing a ball driven member made from elastomer material and including a thrust load path bypassing the motor will provide the feature that fulfils the requirements of the surgeon, namely a satisfactory noise and vibration level and a good feel of the surgical motor. It is contemplated by this invention that the drive shaft driven by the motor will include a coupling that is adapted to receive diametrically opposed balls made from an elastomer material and the balls are interconnected to a driven shaft. The transfer of rotary motion by this method reduces noise and vibration. To further enhance the operation of the motor the thrust loads according to this invention are diverted to bypass the motor so that the motor is designed to accommodate only radial loads. This aspect of the invention in addition to the other features noted above, enhances the life of the motor.